After messages have been pulled over the network one time, subsequent access to those messages does not cause additional network traffic. It's also designed to help insulate users from network latency and connectivity issues while they are using Outlook.īy caching users' mailboxes to their computers, Outlook no longer depends on continuous network connectivity for access to user information. ost file) on the user's computer, together with an Offline Address Book (OAB).Ĭached Exchange Mode's purpose is to provide a seamless online and offline Outlook experience. When an Exchange account in Outlook is configured to use Cached Exchange Mode, Outlook works from a local copy of the user's Exchange mailbox that is stored in an offline data file (. Outlook for Mac desktop versions (including 2016) support only Cached Exchange Mode.Ĭached Exchange Mode is the default and recommended configuration for most scenarios except those mentioned under When to use Online Mode.